Pneumatic motor



United States Patent 3,199,415 PNEUMATIC MOTOR Arthur J. Stanton, Bethesda, Md., David F. Anderson, McLean, Va., and George B. Boniface, Parkland, Md., assignors to the United States of America as represented by the Secretary of the Navy Filed June 3, 1957, Ser. No. 663,320

1 Claim. (Cl. 91-699) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This application discloses and claims a portion of a complete system disclosed and claimed in copending application Serial No. 663,319, filed June 3, 1957, now Patent No. 3,177,772, for Rapid Fire Gun System, these applications havinga common assignee.

The present invention relates to a pneumatic motor for an ammunition ejection system used in a projectile directing and firing system which includes a low velocity, rapid fire gun and mount. More particularly, this invention is directed to a piston and cylinder arrangement for driving an empty ammunition case ejection system in a weapon particularly suitable for a saturation zone type of protective or assault fire and which is especially well adapted for shipboard antiaircraft use.

Heretofore, antiaircraft guns of both large and small cal-ibers have been devised for employment against high and low altitude attacking planes. Although the large caliber guns are effective at high altitudes when properly used, these guns are generally ineffective at low altitudes and short ranges because, among other reasons, of their slow rate of fire and the more effective evasive action taken by aircraft at low altitudes. Consequently, guns generally in use against low flying aircraft have been of a small caliber and in the machine gun class in order to obtain a rapid rate of fire and cope with the evasive action of aircraft attempting to avoid the Zone of fire. However, the use of armor around the vital parts of aircraft has increased considerably and it has been found that the smaller caliber guns could make a number of hits without reaching a vital part, and, therefore, the attacking aircraft would, in many cases, continue the attack.

With conventional guns, as the caliber increases, the weight of the many gun components as well as the gun itself increases greatly. Heavier structural members are needed to load and transfer ammunition. The recoil forces generated require heavier mounting and driving structures. Consequently, aboardship the number of guns that can be installed is limited by the weight factor alone. Futhermore, the handling of conventional large caliber case ammunition presents problems because of its size and weight, such ammunition not being adapted to belt or clip type feeding as used in the machine gun class weapons.

The use of large guns and mounts generally prohibits the stowage of ammunition or maintenance of magazines on the same level on which the gun is mounted because of space requirements. Thus, the ammunition stowage is at a lower level, often employing three or more decks of the ship to contain all the necessary equipment. Location below decks complicates the problem of feeding ammunition to large caliber guns and necessitates the installation of elaborate ammunition hoists with associated large gains in overall weight and complexity of the ammunition handling equipment.

The present invention overcomes many of the disadvantages of the prior art weapons in that is provides an automatic, rapid acting, lightweight mechanism for operating a gun ejecting system for ejecting empty ammunition cases from which rocket assisted projectiles of relatively large caliber have been fired. The entire device is relatively small and compact as compared with those of the prior art for use in systems employing similar caliber weapons none of which are capable of handling in any given time interval an equivalent amount of ammunition as handled by the system of the aforementioned application Serial No. 663,319, in which .the present invention is employed.

The gun employed with the present invention is provided with a rifled tube and fires a spin-stabilized rocket propelled projectile. The projectile is enclosed in a symmetrical container or case which functions both as a storage case and as an expendable gun chamber when the projectile is fired. The projectile is fired by the ignition of a reduced powder charge with-in the container and is propelled through the barrel at a relatively low velocity. While within the rifled gun barrel, the rocket propellant motor is ignited by the 'hot gases of the reduced powder charge and thereafter the projectile accelerates to a much' higher velocity comparable to conventional projectiles during flight. Suflicient spin is imparted by the rifled tube of the launcher to make the rocket stable as it emerges from the tube. The canted nozzles of the rocket motor provide additional spin during flight. The conventional recoil .is substantially reduced because of the low firing pressures produced.

Machine gun rates-of-ifire are obtained by the use of expendable gun chambers made feasible by the low powder pressure created when each round is fired. The employment of the expendable gun chambers makes possible the moving of the rocket assisted ammunition laterally into axial alignment with the gun barrel without the necessity of axial ramming and extracting operations as is common with conventional cased ammunition.

It is, therefore, an object of the present invention to provide a gas operated piston arrangement for .a rapid fire weapon system and which includes fluid by-pass features to permit buffering of the piston at the end port-ion of its driving stroke and for returning the piston to its initial position.

Another object is to provide a pneumatic piston motor which includes venting passages for venting a portion of the piston driving gases during the driven stroke of the piston and after the remainder of the driving gases have bypassed the piston to buffer the latter near the end of its driven stroke, the by-passed gases returning the piston to its initial position.

Yet another object of the present invention resides in the provision of a gas operated piston mot-or which includes venting passages for venting piston driving gases during the driven stroke and for venting cushioning and piston return gases during the return stroke.

An additional object is to provide a gas operated piston motor in which the piston is fluid buffered on both its driven and return strokes.

A further object of the present invention resides in the provision of a piston motor which includes shock abs-orbing features for all moving parts.

- Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional View of the right hand case ejection cylinder of the present invention;

FIG. 2 is a transverse sectional view of the gas cylinder portion of the case ejection cylinder of FIG. 1 taken on a line substantially corresponding to line 2-2 of FIG. 1;

FIG. 3'is an enlarged perspective view of the floating check valve used in the fluid buffer piston of FIG. 1; and

' FIG. 4 is an enlarged perspective view of the fluid buffer piston used in the buffer cylinder of FIG. 1.

A gas-operated piston cylinder 932 is illustrated in FIG. 1. -A later-ally bored port 952 provides communication between the space forward of piston 934 and a port in the gun mechanism (not illustrated). High pressure gases 7 created in the gun barrel when a round is fired, are periodically admitted to cylinder 932 via port 952.

As gas enters the piston cylinder 932, the piston is driven rearwardly and at an intermediate position of its stroke, the driving high pressure gases are permitted to by-pass ahead of the piston by means of a series of longitudinal slots 959 provided in the cylinder wall. At a point intermediate the length of slots 959 .a series of apertures 961 are provided in the cylinder wall and in communication with the atmosphere. These apertures 961 are uncovered by the piston during its rearward travel to release a major portion of the high pressure gas to the atmosphere. Additional piston travel will compress the by-passed gas ahead of the piston thus aiding spring 962, later described, in buffering the piston on this rearward stroke. The by-pas-sed gas also furnishes .suflicient energy to return the piston to its forward position. During the forward movement of the piston, apertures 961 again will be uncovered to permit dispersal of the residual buffering gases.

Referring now to the buffer and reservoir cytlinder 931, an inner fluid buffer piston cylinder 963 is surrounded by and communicates with an annular fluid reservoir cylinder 964 integrally formed therewith. Inner cylinder 963 receives the piston forward shaft extension 935 to which is threadably secured a buffer piston 965, also illustrated in FIG. 4. The return spring 962, previously mentioned, is used to return and retain the piston 934 in a forward position. This spring 962 abuts a cylindrical sleeve 966 at the rearward end of cylinder 963, the other end of the spring engaging a rear face of the buffer piston 965. Com-.

munication of buffer cylinder 963 with the fluid reservoir 964 is provided by a series of ports 967 formedin the buffer cylinder Walls adjacent the rearward end of the buffer cylinder and an additional series of ports 968 are provided adjacent its forward end, for a purpose to be forward end in which a movable check valve 971 is re tained by means of a threaded retaining ring 972. The check valve tabuts and seals a rearwardly extending, fluid buffer passage 973 which communicates with the rear face of the piston by means of ports 974. These ports 974 are formed in a reduced diameter rearwardly extending por tion 975 of the piston 965 and are aligned with longitudinal cross slots 976 in the rear piston face .and the external surface of the piston portion 975. These ports and slots permit free passage of the fluid and compensate for the area restriction caused by the piston return spring 962 which might otherwise tend to buffer the piston 965 during its return stroke.

The check valve 971 has a rear face 977 for sealing passage 973. This valve 971 is also provided with a series of raised, guide lug-s'978, FIG. 3, formed about its periphery, each pair of lugs defining a depressed fluid passage 979 therebetween. The front face of the valve is centrally bored at 981, and the adjacent walls of the valve which define this bore are cross slotted as at 982 to allow free passage of fluid from the buffer passage 973 through the depressed passages 979 and the slots 982 as the buffer piston is driven rearwardly by the high pressure gases.

In operation, the buffer piston 965 is moved rearwardly against spring tension upon actuation of the gas operated piston 934, the buffer piston displacing a portion of the fluid from its cylinder 963 into reservoir 964 by mean-s of slots 967. The fluid then moves into buffer cylinder 963 in front of the rearwardly moving piston 965 by means of slots 968 in the forward end walls of the cylinder. Additionally, some of the fluid at the opposite side of the piston 965 passes through the piston buffer passage 973 unseating the check valve 97-1 and allowing fluid to pass to the front face of the piston. On the forward stroke of buffer piston 965, fluid is blocked by the now seated check valve 971 and most of the fluid in front of the piston is caused to move out through slots 968 at the forward end of the cylinder. As the piston 965 [approaches these slots, a throttling action takes place as entrapped fluid passes a series of longitudinal grooves 983 formed in the outer surface of the piston 965. Any additional fluid is vented through a small, centrally bored orifice 984 which communicates with the reservoir 964 by means of a connecting passage 985 formed betweenthe exterior surface of the front wall of the buffer piston cylinder 963 and the interior surface of the front wall of the reservoir cylinder. 964.

A threaded bore 986 is formed in the front wall of the reservoir cylinder adjacent the passage 985 to receive a fluid expansion cylinder 933. The cylinder 933 contains a spring urged fluid sealed piston and shaft assembly 987 biased in a rearward direction in the cylinder 933. The shaft 988 of piston and shaft assembly 987 extends through and beyond a cylinder sealing end cap 989. The expan sion cylinder direct-1y communicates with reservoir 964 via passage 985 to maintain a constant pressure on the bufiing fluid. pansion chamber will fill the void created by withdrawal of shaft 935 from cylinder 963.

Referring once again to cylinder 932 in FIG. 1, rod

936 is fixed to crosshead 938, which forms .a part of a shell ejection system (not illustrated). The ejection system is described in detail in copending application Serial No. 663,321, filed June 3, .1957, now US. Patent No. 3,152,511.

We claim: A pneumatic motor comprising: a first cylinder having inlet and exhaust ports, and a plurality of longitudinal grooves on its inner wall; a source of pressurized gas connected to said inlet port; a power piston reciprocable in said cylinder, said power piston dividing said cylinder into first and second chambers, and said power piston being movable during a working stroke from a first position to a second position by the force of pressurized gas selectively admitted through said inlet port into said first chamber of said cylinder;

said longitudin-al groove-s providing a bypass path whereby a portion of the pressurized gas is bypassed around i said power piston from said first chamber to said second chamber during the working stroke of said power piston, thereby .to provide a cushioning of said power piston at the end of its working stroke; a second cylinder; a butter piston connected to and movable with said power piston and .reciprocable in said second cylinder between first and second posit-ions corresponding to As piston 965 move s rearwardly, fluid from the excheck valve means in said buffer piston operative to permit fluid flow through said buffer piston during the working stroke of said power piston, and further operative to block such flow during the return stroke of said pistons from their respective second positions to their respective first positions; and

throttling means in said second cylinder and on said buffer piston operative to provide a progressively increasing resistance to the advance of the buffer piston on its return stroke.

References Cited by the Examiner UNITED STATES PATENTS 523,242 7/94 Smith 929 528,299 10/94 Kidd 91232 Kidd 60-20 B all 929 Berry 91399 Townsend 91-50 Humes 91-402 Stoney. Renter.

Hewitt 91--26 FOREIGN PATENTS Great Britain.

SAMUEL LEVINE, Primary Examiner.

SAMUEL BOYD, ARTHUR M. HORTON, SAMUEL FEINBERG, FRED E. ENGELTH-ALER, Examiners. 

